How does your academic probation system work? If you got a 1.3 on a 4.0 scale and you needed a 3 to avoid probation, it was literally impossible to avoid probation for your second term. Your B's are unfortunate, but the way I see it you have three solid arguments for not being expelled:
a) It was impossible to get off of probation in your second semester, so remaining on probation in your third semester solely because of your first semester's performance (when you were acclimating to being in the US) is equivalent to remaining on probation for one semester if you look at it from the perspective of potential outcomes.
b) You got grades that were above the threshold for probation for your other two terms, indicating that your lack of performance was over a year behind you at this point and there was a major correction.
c) If you are only permitted to take three classes in a term, and the university knowingly allowed you to enroll in a Thesis course, they set you up to fail. If you had a 2.5 GPA entering your 3rd semester (and there are 3 courses per semester) you would need exactly 3 As to equal a 3.0 GPA (once again assuming 3 courses per term). Essentially by allowing you to remain in your program since that first semester, the university has demonstrated that either they did not care about your success as a student, they were not able to do basic math, or that they were planning not to expel you when this outcome inevitably happened.
EDIT: To elaborate on the point re: basic math. If you had a 1.3 your first semester (3 courses), and you have 5 courses (because a Thesis course is expected of you) remaining which count towards your GPA, you would need a 4.02 GPA average over your remaining courses to not be expelled.
I would bring this up with your advisor, and appeal to the university regardless of what your advisor says (unless they have an answer that makes such an appeal irrelevant in a positive way).
